The present invention concerns force sensors for use with weighing machines. The invention is particularly concerned with what are known as vibrating beam force sensors and the manner in which they are mounted within load cells. Such sensors are well known and essentially comprise either two parallel beams or a central beam surrounded by two outer beams, the sensor being made from a single piece of metal. In operation the ends of such a sensor are clamped to a loading frame which forms part of a load cell. The sensor is clamped so that it is under tension and the beam is driven into flexural vibration by suitable transducers. The vibrational frequency of the beam changes in response to variations in tension and these changes are measured to provide a measurement of the applied tension and thus of the applied load.
The clamping of vibrating beam force sensors has a critical effect on their performance. An ideal clamp will produce only a force perpendicular to the surface to which clamping is required. However most clamps produce forces parallel to the plane in which clamping is required.